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| United States Patent |
6,010,537
|
|
Konno
, et al.
|
January 4, 2000
|
Zoom lens system having an image blur compensation function
Abstract
A zoom lens system has, from the object side, a first lens unit, a second
lens unit with an aperture stop, and a third lens unit. In this zoom lens
system, zooming is performed by varying the distances between these lens
units; focusing from the infinite distance to the closest distance is
performed by moving the first lens unit toward the object side along the
optical axis; image blur compensation is performed by decentering an image
blur compensating lens unit included in the third lens unit.
| Inventors:
|
Konno; Kenji (Daito, JP);
Nagata; Hideki (Sakai, JP)
|
| Assignee:
|
Minolta Co., Ltd. (Osaki, JP)
|
| Appl. No.:
|
135469 |
| Filed:
|
August 17, 1998 |
Foreign Application Priority Data
| Aug 19, 1997[JP] | 9-222734 |
| Aug 19, 1997[JP] | 9-222735 |
| Current U.S. Class: |
359/389; 359/687; 359/688 |
| Intern'l Class: |
G02B 015/14 |
| Field of Search: |
359/686,689,688,687
|
References Cited
U.S. Patent Documents
| 5249079 | Sep., 1993 | Umeda et al. | 359/554.
|
| 5760957 | Jun., 1998 | Suzuki | 359/557.
|
| Foreign Patent Documents |
| 5-224160 | Sep., 1993 | JP.
| |
| 7-027978 | Jan., 1995 | JP.
| |
| 7-318865 | Dec., 1995 | JP.
| |
| 8-114771 | May., 1996 | JP.
| |
Primary Examiner: Epps; Georgia
Assistant Examiner: Lucas; Michael A.
Attorney, Agent or Firm: Sidley & Austin
Claims
What is claimed is:
1. A zoom lens system comprising, in order from an object side of said zoom
lens system:
a first lens unit movable along an optical axis during a focusing
operation;
a second lens unit including an aperture stop; and
a third lens unit including, at least in part, an image blur compensating
lens unit, said image blur compensating lens unit being adapted to
compensate for an image blur caused by vibration of the zoom lens system,
wherein distances between said first, second, and third lens units are
variable so as to change a focal length of the entire zoom lens system.
2. A zoom lens system in accordance with claim 1,
wherein said second lens unit is provided on an image side of said first
lens unit with a first variable air gap in between.
3. A zoom lens system in accordance with claim 1,
wherein said second lens unit is provided on an object side of said third
lens unit with a second variable air gap in between.
4. A zoom lens system in accordance with claim 1,
wherein at least a part of said third lens unit moves in a direction
perpendicular to an optical axis of the zoom lens system.
5. A zoom lens system in accordance with claim 1,
wherein said image blur compensating lens unit consists of a single lens
element.
6. A zoom lens system in accordance with claim 1,
wherein said image blur compensating lens unit consists of a doublet lens
element formed by cementing two lens elements together.
7. A zoom lens system comprising, in order from an object side of said zoom
lens system:
a first lens unit;
a second lens unit including an aperture stop; and
a third lens unit including, at least in part, an image blur compensating
lens unit, said image blur compensating lens unit, having a single lens
element, is adapted to compensate for an image blur caused by vibration of
the zoom lens system,
wherein distances between said first, second, and third lens units are
variable so as to change a focal length of the entire zoom lens system.
8. A zoom lens system in accordance with claim 7,
wherein said second lens unit is provided on an image side of said first
lens unit with a first variable air gap in between.
9. A zoom lens system in accordance with claim 7,
wherein said second lens unit is provided on an object side of said third
lens unit with a second variable air gap in between.
10. A zoom lens system in accordance with claim 7,
wherein at least a part of said third lens unit moves in a direction
perpendicular to an optical axis of the zoom lens system.
11. A zoom lens system comprising, in order from an object side of said
zoom lens system:
a first lens unit having a positive optical power;
a second lens unit having a negative optical power;
a third lens unit having a positive optical power, said third lens unit
being adapted for decentering so as to compensate for image blur caused by
vibration of the zoom lens system; and
a fourth lens unit having a negative optical power, said fourth lens unit
being provided at an image-side end of the zoom lens system,
wherein tho following conditions are fulfilled:
1.5<f1/fW<6.0
-1.0<f2/fW<-0.20
-1.5<fB/fR<-0.3
0.8<fB/fW<4.0
where
f1 represents a focal length of the first lens unit,
f2 represents a focal length of the second lens unit,
fW represents a focal length of the entire zoom lens system in a shortest
focal length condition,
fB represents a focal length of the third lens unit, and
fR represents a focal length of the fourth lens unit.
12. A zoom lens system in accordance with claim 11,
wherein said third lens unit consists of a doublet lens element formed by
cementing two lens elements together.
13. A zoom lens system in accordance with claim 11,
wherein said second lens unit is movable along an optical axis during a
focusing operation.
14. A zoom lens system in accordance with claim 13, wherein for a focusing
operation from an infinite object distance to a closest object distance,
said second lens unit is adapted to move along said optical axis toward
said object side.
15. A zoom lens system in accordance with claim 11,
wherein an aperture stop is provided in one of said first, second, and
fourth lens units.
16. A zoom lens system having a plurality of lenses, said plurality of
lenses including, in order from an object side of said zoom lens system:
a first lens unit movable along an optical axis during a focusing
operation;
a second lens unit including an aperture stop; and
a third lens unit including, at least in part, an image blur compensating
lens unit, said image blur compensating lens unit being adapted to
compensate for an image blur caused by vibration of the zoom lens system
by decentering along a direction perpendicular to said optical axis,
wherein distances between said first, second, and third lens units are
variable so as to change a focal length of the entire zoom lens system.
17. A zoom lens system comprising, in order from an object side of said
zoom lens system:
an object side lens unit having a positive optical power and located at the
object side of said zoom lens system;
a focusing lens unit having a negative optical power and located at an
image side of said object side lens unit, said focusing lens unit being
movable toward the object side of said zoom lens system during a focusing
operation;
a first succeeding lens unit including an aperture stop; and
a second succeeding lens unit including, at least in part, an image blur
compensating lens unit, said image blur compensating lens unit being
adapted to compensate for an image blur caused by vibration of said zoom
lens system,
wherein distances between said object side, focusing, first succeeding and
second succeeding lens units are variable so as to change a focal length
of the entire zoom lens system.
18. A zoom lens system in accordance with claim 17,
wherein said first succeeding lens unit has a positive optical power.
19. A zoom lens system in accordance with claim 17,
wherein said second succeeding lens unit has a positive optical power.
20. A zoom lens system in accordance with claim 17,
wherein at least a part of said second succeeding lens unit moves in a
direction perpendicular to an optical axis of the zoom lens system.
21. A zoom lens system in accordance with claim 17,
wherein said image blur compensating lens unit consists of a single lens
element.
22. A zoom lens system in accordance with claim 17,
wherein said image blur compensating lens unit consists of a doublet lens
element formed by cementing two lens elements together.
Description
This application is based on applications Nos. H9-222734 and H9-222735
filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom lens system having an image blur
compensation function, and more specifically to a zoom lens system having
an image blur compensation function for use in a camera for shooting
silver-halide film pictures, a camera for shooting video pictures (moving
and still pictures), or a single-lens reflex camera, for example.
2. Description of the Prior Art
Conventionally, various types of zoom lens systems having an image blur
compensation function have been proposed. For example, Japanese Laid-open
Patent Application No. H7-27978 proposes a zoom lens system that is
composed of, from the object side, a positive lens unit, a negative lens
unit, a negative lens unit, and a positive lens unit and in which a single
lens element included in the fourth lens unit or a doublet lens element
constituting the third lens unit is moved in a direction perpendicular to
the optical axis so as to compensate for an image blur. Moreover, Japanese
Laid-open Patent Application No. H5-224160 proposes a zoom lens system
that is composed of, from the object side, a positive lens unit, a
negative lens unit, a positive lens unit, a positive lens unit, and a
negative lens unit and in which the fifth lens unit is divided into a
front lens unit having a negative optical power and a rear lens unit
having a positive optical power. Here, image blur compensation is achieved
by moving the front lens unit (composed of a plurality of lens elements).
Furthermore, Japanese Laid-open Patent Application No. H7-318865 proposes
a zoom lens system that is composed of, from the object side, a positive
lens unit, a negative lens unit, a positive lens unit, a positive lens
unit, and a negative lens unit and in which a doublet lens element
constituting the fourth lens unit is moved in a direction perpendicular to
the optical axis so as to compensate for an image blur. In addition,
Japanese Laid-open Patent Application No. H8-114771, by the same inventors
as the present invention, proposes a zoom lens system that is composed of,
from the object side, a positive lens unit, a negative lens unit, a
positive lens unit, and a positive lens unit and in which image blur
compensation is achieved by moving a single lens element constituting the
fourth lens unit.
In the zoom lens systems proposed in Japanese Laid-open Patent Applications
Nos. H7-27978 and H7-318865 mentioned above, an aperture stop is provided
in the fourth lens unit. On the other hand, in the zoom lens systems
proposed in Japanese Laid-open Patent Applications Nos. H5-224160 and
H8-114771 mentioned above, an aperture stop is provided in the third lens
unit. In some of such conventional zoom lens systems, an image blur
compensating lens unit and an aperture stop are provided in one zoom unit,
and this inconveniently causes interference between the driving mechanism
for driving the aperture stop and the driving mechanism for image blur
compensation. To avoid this, it is inevitable to make the entire zoom unit
including the driving mechanisms unduly large. This spoils compactness of
the entire zoom lens system, making the camera as a whole unduly large.
Similarly, in a zoom lens system in which a focusing lens unit and an
aperture stop are provided in one zoom unit, or in a zoom lens system in
which a focusing lens unit and an image blur compensating lens unit are
provided in one zoom unit, interference between the driving mechanism for
focusing and the driving mechanism for driving the aperture stop or for
image blur compensation cannot be avoided unless the camera as a whole is
made unduly large.
Moreover, in the zoom lens system proposed in Japanese Laid-open Patent
Application No. H5-224160 and the like, the type of aberration called the
off-axial image-point movement error, which is one of the aberrations
caused by camera shake, is not properly corrected. Even if satisfactory
imaging performance is secured during image blur compensation, large
off-axial image-point movement errors occur unless distortion is properly
corrected. This causes blurring of an image in its off-axial area when
image blur compensation lasts for a relatively long time. In addition,
since the front lens unit that is moved to achieve image blur compensation
is composed of a plurality of lens elements, even though it is possible to
correct the axial lateral chromatic aberration that occurs during image
blur compensation, the weight of the image blur compensating lens unit is
too large to be comfortably borne by the driving mechanism for image blur
compensation. In contrast, in a zoom lens system that has an image blur
compensating lens unit composed of a single lens element, the weight to be
borne by the driving mechanism for image blur compensation is minimal, but
it is impossible to correct the axial lateral chromatic aberration that
occurs when decentering is effected. Furthermore, with some zoom lens
systems for which no specific focusing method is disclosed, it is
difficult to secure satisfactory imaging performance for a closest
distance object because they do not provide appropriate focusing solutions
despite having an image blur compensation function.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a zoom lens system having
an image blur compensation function that offers excellent optical
performance in a compact structure.
To achieve the above object, according to one aspect of the present
invention, a zoom lens system is provided with, from the object side, a
first zoom unit that is moved for focusing, a second zoom unit having an
aperture stop, and a third zoom unit including an image blur compensating
lens unit that is moved for image blur compensation. This zoom lens system
performs zooming by varying the distances between these zoom units.
To achieve the above object, according to another aspect of the present
invention, a zoom lens system is provided with, from the object side, a
first lens unit having a positive optical power, a second lens unit having
a negative optical power, a third lens unit having a positive optical
power, and a fourth lens unit having a negative optical power. In this
structure, the fourth lens unit is disposed at the image-side end, and the
third lens unit disposed immediately on the object side of the fourth lens
unit acts as an image blur compensating lens unit by being decentered in a
direction perpendicular to the optical axis so as to achieve image blur
compensation. Additionally, the zoom lens system is so designed that the
ratios of the focal lengths f1 and f2 of the first and second lens units
to the focal length fW of the entire zoom lens system at the wide-angle
end fulfill the conditions 1.5<f1/fW<6.0, and -1.0<f2/fW<-0.20, that the
ratio of the focal length fB of the third lens unit to the focal length fR
of the fourth lens unit fulfills the condition -1.5<fB/fR<-0.3, and that
the ratio of the focal length fB of the third lens unit to the focal
length fW of the entire zoom lens system at the wide-angle end fulfills
the condition 0.8<fB/fW<4.0.
BRIEF DESCRIPTION OF THE DRAWINGS
This and other objects and features of this invention will become clear
from the following description, taken in conjunction with the preferred
embodiments with reference to the accompanied drawings in which:
FIG. 1 is a lens arrangement diagram of the zoom lens system of a first
embodiment of the present invention;
FIGS. 2A to 2I are graphic representations of the longitudinal aberrations
observed before decentering in an infinite-distance shooting condition in
the first embodiment;
FIGS. 3A to 3I are graphic representations of the longitudinal aberrations
observed before decentering in a closest-distance shooting condition in
the first embodiment;
FIGS. 4A to 4E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
an infinite-distance shooting condition in the first embodiment;
FIGS. 5A to 5E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
an infinite-distance shooting condition in the first embodiment;
FIGS. 6A to 6E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
a closest-distance shooting condition in the first embodiment;
FIGS. 7A to 7E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
a closest-distance shooting condition in the first embodiment;
FIG. 8 is a lens arrangement diagram of the zoom lens system of a second
embodiment of the present invention;
FIGS. 9A to 9I are graphic representations of the longitudinal aberrations
observed before decentering in an infinite-distance shooting condition in
the second embodiment;
FIGS. 10A to 10I are graphic representations of the longitudinal
aberrations observed before decentering in a closest-distance shooting
condition in the second embodiment;
FIGS. 11A to 11E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
an infinite-distance shooting condition in the second embodiment;
FIGS. 12A to 12E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
an infinite-distance shooting condition in the second embodiment;
FIGS. 13A to 13E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
a closest-distance shooting condition in the second embodiment;
FIGS. 14A to 14E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
a closest-distance shooting condition in the second embodiment;
FIG. 15 is a lens arrangement diagram of the zoom lens system of a third
embodiment of the present invention;
FIGS. 16A to 16I are graphic representations of the longitudinal
aberrations observed before decentering in an infinite-distance shooting
condition in the third embodiment;
FIGS. 17A to 17I are graphic representations of the longitudinal
aberrations observed before decentering in a closest-distance shooting
condition in the third embodiment;
FIGS. 18A to 18E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
an infinite-distance shooting condition in the third embodiment;
FIGS. 19A to 19E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
an infinite-distance shooting condition in the third embodiment;
FIGS. 20A to 20E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the wide-angle end in
a closest-distance shooting condition in the third embodiment;
FIGS. 21A to 21E are graphic representations of the meridional lateral
aberrations observed before and after decentering at the telephoto end in
a closest-distance shooting condition in the third embodiment; and
FIG. 22 is a block diagram showing the control system for moving the image
blur compensating lens unit of the first embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, zoom lens systems having an image blur compensation function
embodying the present invention will be described with reference to the
corresponding drawings. FIGS. 1, 8, and 15 show the lens arrangement of
the zoom lens systems of the first to third embodiments, respectively, as
observed at the wide-angle end [W] (i.e. in the shortest focal length
condition). In each lens arrangement diagram, arrow mi (i=1, 2, 3, . . . )
schematically shows the movement of the ith lens unit (Gri) during zooming
from the wide-angle end [W] to the telephoto end [T]. Moreover, in each
lens arrangement diagram, a surface marked with ri (i=1, 2, 3, . . . ) is
the ith surface counted from the object side, and a surface ri marked with
an asterisk (*) is an aspherical surface. Furthermore, di (i=1, 2, 3, . .
. ) represents the ith axial distance counted from the object side, though
only those axial distances between the lens units that vary with zooming
are shown. Note that, in each lens arrangement diagram, arrow mD indicates
the translational decentering of the image blur compensating lens unit
(i.e. the movement in a direction perpendicular to the optical axis), and
arrow mF indicates the focusing movement of the focusing lens unit.
In the first embodiment, the zoom lens system is composed of five lens
units that are, from the object side, a first lens unit having a positive
optical power (Gr1), a second lens unit having a negative optical power
(Gr2), a third lens unit having a positive optical power (Gr3), a fourth
lens unit having a positive optical power (Gr4), and a fifth lens unit
having a negative optical power (Gr5). As indicated by arrows m1 to m5 in
FIG. 1, during zooming from the wide-angle end [W] to the telephoto end
[T], the lens units are moved in such a way that the distance between the
first and second lens units (Gr1 and Gr2) increases, that the distance
between the second and third lens units (Gr2 and Gr3) decreases, that the
distance between the third and fourth lens units (Gr3 and Gr4) decreases,
and that the distance between the fourth and fifth lens units (Gr3 and
Gr5) decreases. Note that, between the surface provided at the image-side
end of the second lens unit (Gr2) and the surface provided at the
object-side end of the third lens unit (Gr3), an aperture stop (S) is
disposed which is moved together with the third lens unit (Gr3) during
zooming.
In the zoom lens system of the first embodiment, each lens unit is
composed, from the object side, as follows. The first lens unit (Gr1) is
composed of a doublet lens element formed by cementing together a negative
meniscus lens element convex to the object side and a positive biconvex
lens element, and a positive meniscus lens element convex to the object
side. The second lens unit (Gr2) is composed of a negative meniscus lens
element convex to the object side, a negative biconcave lens element, a
positive biconvex lens element, and a negative meniscus lens element
concave to the object side. The third lens unit (Gr3) is composed of a
positive biconvex lens element, a positive meniscus lens element convex to
the object side, and a negative meniscus lens element convex to the object
side. The fourth lens unit (Gr4) is composed of a doublet lens element
formed by cementing together a positive biconvex lens element and a
negative meniscus lens element convex to the image side. The fifth lens
unit (Gr5) is composed of a positive meniscus lens element convex to the
image side, and a negative meniscus lens element concave to the object
side.
In the zoom lens system of the first embodiment, the second lens unit (Gr2)
serves as a focusing lens unit (GF), and the fourth lens unit (Gr4) serves
as an image blur compensating lens unit (GB). That is, as indicated by
arrow mF in FIG. 1, the second lens unit (Gr2) is moved along the optical
axis toward the object side so as to achieve focusing from an infinite
distance object to a closest distance object, and, as indicated by arrow
mD in FIG. 1, the fourth lens unit (Gr4) is decentered in a direction
perpendicular to the optical axis so as to achieve image blur
compensation.
In the second embodiment, the zoom lens system is composed of four lens
units that are, from the object side, a first lens unit having a positive
optical power (Gr1), a second lens unit having a negative optical power
(Gr2), a third lens unit having a positive optical power (Gr3), and a
fourth lens unit having a negative optical power (Gr4). As indicated by
arrows m1 to m4 in FIG. 8, during zooming from the wide-angle end [W] to
the telephoto end [T], the lens units are moved in such a way that the
distance between the first and second lens units (Gr1 and Gr2) increases,
that the distance between the second and third lens units (Gr2 and Gr3)
decreases, and that the distance between the third and fourth lens units
(Gr3 and Gr4) decreases. Note that, between the surface provided at the
image-side end of the second lens unit (Gr2) and the surface provided at
the object-side end of the third lens unit (Gr3), an aperture stop (S) is
disposed which is moved together with the third lens unit (Gr3) during
zooming.
In the zoom lens system of the second embodiment, each lens unit is
composed, from the object side, as follows. The first lens unit (Gr1) is
composed of a doublet lens element formed by cementing together a negative
meniscus lens element convex to the object side and a positive biconvex
lens element, and a positive meniscus lens element convex to the object
side. The second lens unit (Gr2) is composed of a negative meniscus lens
element convex to the object side, a negative biconcave lens element, a
positive biconvex lens element, and a negative biconcave lens element. The
third lens unit (Gr3) is composed of a positive biconvex lens element, a
positive meniscus lens element convex to the object side, and a negative
meniscus lens element convex to the object side. The fourth lens unit
(Gr4) is composed of a doublet lens element formed by cementing together a
positive biconvex lens element and a negative meniscus lens element convex
to the image side, a positive meniscus lens element convex to the image
side, and a negative meniscus lens element concave to the object side.
In the zoom lens system of the second embodiment, the second lens unit
(Gr2) serves as a focusing lens unit (GF), and the doublet lens element
included in the fourth lens unit (Gr4) serves as an image blur
compensating lens unit (Gb). That is, as indicated by arrow mF in FIG. 8,
the second lens unit (Gr2) is moved along the optical axis toward the
object side so as to achieve focusing from an infinite distance object to
a closest distance object, and, as indicated by arrow mD in FIG. 8, the
image blur compensating lens unit (Gb) included in the fourth lens unit
(Gr4) is decentered in a direction perpendicular to the optical axis so as
to achieve image blur compensation.
In the third embodiment, the zoom lens system is composed of five lens
units that are, from the object side, a first lens unit having a positive
optical power (Gr1), a second lens unit having a negative optical power
(Gr2), a third lens unit having a positive optical power (Gr3), a fourth
lens unit having a positive optical power (Gr4), and a fifth lens unit
having a negative optical power (Gr5). As indicated by arrows m1 to m5 in
FIG. 15, during zooming from the wide-angle end [W] to the telephoto end
[T], the lens units are moved in such a way that the distance between the
first and second lens units (Gr1 and Gr2) increases, that the distance
between the second and third lens units (Gr2 and Gr3) decreases, that the
distance between the third and fourth lens units (Gr3 and Gr4) decreases,
and that the distance between the fourth and fifth lens units (Gr3 and
Gr5) decreases. Note that, between the surface provided at the image-side
end of the second lens unit (Gr2) and the surface provided at the
object-side end of the third lens unit (Gr3), an aperture stop (S) is
disposed which is moved together with the third lens unit (Gr3) during
zooming.
In the zoom lens system of the third embodiment, each lens unit is
composed, from the object side, as follows. The first lens unit (Gr1) is
composed of a doublet lens element formed by cementing together a negative
meniscus lens element convex to the object side and a positive meniscus
lens element concave to the image side, and a positive meniscus lens
element convex to the object side. The second lens unit (Gr2) is composed
of a negative meniscus lens element convex to the object side, a negative
biconcave lens element, a positive biconvex lens element, a negative
meniscus lens element concave to the object side, and a positive meniscus
lens element convex to the object side. The third lens unit (Gr3) is
composed of two positive biconvex lens elements, and a negative biconcave
lens element. The fourth lens unit (Gr4) is composed of a doublet lens
element formed by cementing together a positive biconvex lens element and
a negative meniscus lens element convex to the image side. The fifth lens
unit (Gr5) is composed of a positive meniscus lens element convex to the
image side, and a negative meniscus lens element concave to the object
side.
In the zoom lens system of the third embodiment, four lens elements (r6 to
r13) included in the second lens unit (Gr2) constitute a focusing lens
unit (Gf), and the fourth lens unit (Gr4) serves as an image blur
compensating lens unit (GB). That is, as indicated by arrow mF in FIG. 15,
the focusing lens unit (Gf) included in the second lens unit (Gr2) is
moved along the optical axis toward the object side so as to achieve
focusing from an infinite distance object to a closest distance object,
and, as indicated by arrow mD in FIG. 15, the entire fourth lens unit
(Gr4) is decentered in a direction perpendicular to the optical axis so as
to achieve image blur compensation.
As described above, in the zoom lens systems of the first to third
embodiments, zooming is achieved by varying the distances between the zoom
units, focusing is achieved by moving the whole (GF) or a part (Gf) of the
second lens unit (Gr2) placed on the object side of the third lens unit
(Gr3) along the optical axis, and image blur compensation is achieved by
decentering the whole (GB) or a part (Gb) of the fourth lens unit (Gr2)
placed on the image side of the third lens unit (Gr3). This structure, in
which at least three zoom units (Gr2 to Gr4) are provided and zooming is
performed by varying the distances between the zoom units, allows ample
freedom in zooming, and thereby makes it possible to realize a
high-zooming-ratio zoom lens system that offers excellent optical
performance.
In general, three separate driving mechanisms are required to drive an
image blur compensating lens unit, an aperture stop, and a focusing lens
unit. For example, in a case where the image blur compensating lens unit
and the aperture stop are provided in one zoom unit, it is necessary to
arrange two driving mechanisms around one lens holding member. Arranging
two driving mechanisms without interference therebetween leads, as
described earlier, to an increased size of the entire zoom unit including
the driving mechanisms. This spoils compactness of the entire zoom lens
system, making the camera as a whole unduly large. In addition, this
complicates not only the arrangement of the driving mechanisms themselves,
but also the arrangement of the power supply units for them.
To solve this problem of interference between driving mechanisms and
similar problems, it is preferable to arrange an image blur compensating
lens unit, an aperture stop, and a focusing lens unit in separate zoom
units as in the zoom lens systems of the first to third embodiments. This
allows the driving mechanisms for the image blur compensating lens unit,
the aperture stop, and the focusing lens unit to be arranged in separate
zoom units. This helps reduce the size of the zoom units and simplify the
design of the driving mechanisms. As a result, it is possible to make the
entire zoom lens system including the driving mechanisms compact without
interference between the driving mechanisms.
In the first to third embodiments, such a structure is realized by
providing the zoom lens system with a first zoom unit (GA) having an
aperture stop (S), a second zoom unit (GF) of which the whole (GF) or a
part (Gf) is moved along the optical axis to achieve focusing, and a third
zoom unit of which the whole (GB) or the part (Gb) is decentered
translationally to achieve image blur compensation. Note that, in these
embodiments, the third lens unit (Gr3) corresponds to the first zoom unit
(GA), the second lens unit (Gr2) corresponds to the second zoom unit (GF),
and the fourth lens unit (Gr4) corresponds to the third zoom unit (GB).
Additionally, in these embodiments, the second lens unit (Gr2)
corresponding to the second zoom unit (GF) is placed on the object side of
the third lens unit (Gr3) corresponding to the first zoom unit (GA), and
the fourth lens unit (Gr4) corresponding to the third zoom unit (GB) is
placed on the image side of the third lens unit (Gr3) corresponding to the
first zoom unit (GA). That is, a focusing lens unit (GF or Gf), an
aperture stop (S), and an image blur compensating lens unit (GB or Gb) are
arranged in this order from the object side. This structure makes it
possible to minimize the size of the image blur compensating lens unit and
the focusing lens unit, and to achieve satisfactory image blur
compensation over the entire range from the infinite-distance shooting
condition to the closest-distance shooting condition. The reasons are as
follows.
First, by placing the focusing lens unit (GF or Gf) on the object side of
the image blur compensating lens unit (GB or Gb), it is possible to keep
constant the object distance with respect to any lens unit placed on the
image side of the focusing lens unit (GF or Gf) regardless of focusing.
That is, the magnification of the image blur compensating lens unit (GB or
Gb) is kept constant regardless of focusing. This helps reduce variations
in the aberrations that occur in the image blur compensating lens unit (GB
or Gb) and the lens units placed on the object side thereof. Accordingly,
the effect of image blur compensation does not vary according to the
object distance, and therefore it is possible to achieve satisfactory
image blur compensation over the entire range from the infinite-distance
shooting condition to the closest-distance shooting condition.
Second, since light beams are dense in the vicinity of the aperture stop
(S), by placing the first zoom unit (GA), which includes the aperture stop
(S), next to the third zoom unit (GB), which constitutes the image blur
compensating lens unit (GB or Gb), it is possible to reduce the diameter
of the image blur compensating lens unit (GB or Gb). This helps reduce the
weight of the image blur compensating lens unit (GB or Gb) and thus the
load to be borne by the driving mechanism for the image blur compensation
lens unit. This in turn helps reduce the size of the driving mechanism for
the image blur compensating lens unit.
Third, since light beams are dense in the vicinity of the aperture stop
(S), by placing the first zoom unit (GA), which includes the aperture stop
(S), next to the second zoom unit (GF), which constitutes the focusing
lens unit (GF or Gf), it is possible to reduce the diameter of the
focusing lens unit (GF or Gf). This helps reduce the weight of the
focusing lens unit (GF or Gf) and thus the load to be borne by the driving
mechanism for the focusing lens unit. This in turn helps reduce the size
of the driving mechanism for the focusing lens unit.
For these reasons, to minimize the size of the image blur compensating lens
unit (GB or Gb) and the focusing lens unit (GF or Gf), and to achieve
satisfactory image blur compensation over the entire range from the
infinite-distance shooting condition to the closest-distance shooting
condition, it is preferable, in a zoom lens system, that a focusing lens
unit (GF or Gf), an aperture stop (S), and an image blur compensating lens
unit (GB or Gb) are arranged in this order from the object side as in the
zoom lens systems of the first to third embodiments.
Where image blur compensation is achieved by inclining the image blur
compensating lens unit with respect to its optical axis, the driving
mechanism for the image blur compensating lens unit needs to have a
driving shaft that goes through the center of rotation. As a result, the
larger the distance between the center of rotation and the image blur
compensating lens unit, the larger the size of the driving mechanism along
th e optical axis. In contrast, where image blur compensation is achieved
by moving the image blur compensating lens unit (GB or Gb) along a
direction perpendicular to the optical axis as in the zoom lens systems of
the first to third embodiments, it is possible to make the driving
mechanism for the image blur compensating lens unit simple and compact.
Where the image blur compensating lens unit is composed of a single lens
element, the number of constituent lens elements is minimal. This makes it
possible to minimize the load to be borne by the driving mechanism for the
image blur compensating lens unit. However, since it is impossible to
correct chromatic aberration properly with a single lens element while the
image blur compensating lens unit is decentered, it is impossible to
correct the axial lateral chromatic aberration that occurs during
decentering. On the other hand, where the image blur compensating lens
unit is composed of a plurality of lens elements so that the chromatic
aberration occurring therein is corrected properly, the load to be borne
by the driving mechanism for the image blur compensating lens unit is
unduly heavy. To avoid these inconveniences, it is preferable that the
image blur compensating lens unit (GB or Gb) be composed of a single
doublet lens element as in the zoom lens systems of the first to third
embodiments. This makes it possible to correct the axial lateral chromatic
aberration that occurs during image blur compensation and simultaneously
minimize the load to be borne by the driving mechanism for the image blur
compensating lens unit.
Where, as described above, the image blur compensating lens unit is
composed of a single doublet lens element, the axial optical path length
of the image blur compensating lens unit is minimal. In this case, even if
a focusing lens unit, an image blur compensating lens unit, and an
aperture stop are arranged in this order from the object side, the axial
optical path length from the focusing lens unit to the aperture stop is
only moderately long, and thus the effective diameter of the focusing lens
unit is kept small. Accordingly, even where the image blur compensating
lens unit is composed of a single doublet lens element, as long as the
focusing lens unit, the image blur compensating lens unit, and the
aperture stop are provided in separate zoom units, it is possible to
achieve the same effect as in the zoom lens systems of the first to third
embodiments.
As described heretofore, in the first to third embodiments, the zoom lens
system is composed of, from the object side, a first lens unit having a
positive optical power (Gr1), a second lens unit having a negative optical
power (Gr2), and other lens units (Gr3 . . . ) that are each composed of
at least one zoom unit. In this zoom lens system, during zooming from the
wide-angle end [W] to the telephoto end [T], both the first and second
lens units (Gr1 and Gr2) are moved toward the object side so that the
distance between the first and second lens units (Gr1 and Gr2) increases.
In this zoom lens system, the lens units (Gr3 . . . ) other than the first
and second lens units includes a last lens unit (GR) placed at the
image-side end and composed of negatively powered lens units and an image
blur compensating lens unit (GB or Gb) placed next to the last lens unit
(GR) on the object side thereof and composed of positively powered lens
units. In this zoom lens system, image blur compensation is achieved by
decentering the image blur compensating lens unit (GB or Gb) in a
direction perpendicular to the optical axis. This zoom lens structure
having an image blur compensation function (hereafter referred to as "the
characteristic zoom lens structure") is suitable for use in single-lens
reflex cameras, and has various advantages as described below.
In the characteristic zoom lens structure described above, the distance
between the first and second lens units (Gr1 and Gr2) is minimal at the
wide-angle end [W]. That is, the entire zoom lens system exhibits a
retrofocus-type power distribution at the wide-angle end [W]. Thus, it is
possible to secure a sufficient back focal length. In contrast, the
distance between the first and second lens units (Gr1 and Gr2) is maximal
at the telephoto end [T]. That is, the entire zoom lens system exhibits a
telephoto-type power distribution at the telephoto end [T]. Thus, it is
possible to reduce the total length of the zoom lens system at the
telephoto end [T]. In addition, since the first lens unit (Gr1) is not
kept in a fixed position during zooming as in video zooming, that is, both
the first and second lens units (Gr1 and Gr2) are moved toward the object
side during zooming from the wide-angle end [W] to the telephoto end [T],
it is possible to reduce the total length of the entire zoom lens system
at the wide-angle end [W].
In the characteristic zoom lens structure described above, it is preferable
that at least one of Conditions (1) to (3) described below be fulfilled.
Conditions (1) and (2) define the conditions to be fulfilled to keep the
optical powers of the first and second lens units (Gr1 and Gr2) in
appropriate ranges, and Condition (3) defines the condition to be
fulfilled to keep the back focal length in an appropriate range.
1.5<f1/fW<6.0 (1)
-1.0<f2/fW<-0.20 (2)
0.85<LBW/Ymax<2.5 (3)
where
f1 represents the focal length of the first lens unit (Gr1);
f2 represents the focal length of the second lens unit (Gr2);
fW represents the focal length of the entire zoom lens system at the
wide-angle end [W];
LBW represents the back focal length at the wide-angle end [W]; and
Ymax represents half the diagonal length of the image screen.
If the upper limit of Condition (1) is exceeded, the optical power of the
first lens unit (Gr1) is too weak. This makes the telephoto-type power
distribution at the telephoto end [T] less significant, and thus makes the
total length of the zoom lens system unduly large at the telephoto end
[T]. In contrast, if the lower limit of Condition (1) is exceeded, whereas
the total length of the zoom lens system at the telephoto end [T] can be
effectively reduced, the diameter of the first lens unit (Gr1) needs to be
increased in order to secure sufficient off-axial light beams at the
wide-angle end [W], and in addition the optical power of the first lens
unit (Gr1) becomes so strong that it is difficult to correct aberrations
properly.
If the upper limit of Condition (2) is exceeded, the optical power of the
second lens unit (Gr2) is too weak. As a result, the diameter of the first
lens unit (Gr1) needs to be increased in order to secure sufficient
off-axial light beams at the wide-angle end [W]. Moreover, the
retrofocus-type power distribution at the wide-angle end [W] becomes so
insignificant that it is difficult to secure a sufficient back focal
length. In contrast, if the lower limit of Condition (2) is exceeded, the
Petzval sum becomes excessively great in the negative direction, and this
makes it difficult to correct astigmatism and curvature of field properly.
Moreover, the telephoto-type power distribution at the telephoto end [T]
becomes so insignificant that the total length of the zoom lens system
becomes unduly large at the telephoto end [T].
If the upper limit of Condition (3) is exceeded, the back focal length
becomes too large, with the result that the total length of the zoom lens
system becomes unduly large. In contrast, if the lower limit of Condition
(3) is exceeded, the back focal length becomes too small, and this makes
it difficult to dispose a TTL (i.e. through the taking lens) mirror.
Within the range defined by Condition (1), it is more preferable that
Condition (1') below be fulfilled. Fulfillment of Condition (1') makes it
possible to obtain higher optical performance.
2.5<f1/fW<6.0 (1')
Within the range defined by Condition (3), it is more preferable that
Condition (3') below be fulfilled. Fulfillment of Condition (3') makes it
possible to realize a more compact zoom lens system.
0.85<LBW/Ymax<1.35 (3')
In general, in a zoom lens system for a single-lens reflex camera, lens
elements are so arranged that those closer to the image-side end are
smaller in diameter, and thus in weight, than those closer to the
object-side end. To perform image blur compensation, the image blur
compensating lens unit needs to be driven by a driving mechanism dedicated
thereto. To reduce the load to be borne by this driving mechanism, it is
essential to reduce the size and weight of the image blur compensating
lens unit. For this reason, it is preferable to use a lens unit disposed
as close as possible to the image-side end as the image blur compensating
lens unit. In the zoom lens systems of the first to third embodiments, the
lens unit placed immediately on the object side of the last lens unit (GR)
is used as the image blur compensating lens unit (GB or Gb). This helps
reduce the load to be borne by the driving mechanism for the image blur
compensating lens unit, and thus makes it possible to reduce the size of
the driving mechanism for the image blur compensating lens unit. Moreover,
since, as described above, a zoom lens system for a single-lens reflex
camera generally has smaller lens elements disposed closer to the
image-side end, it is more preferable to use, as in the zoom lens systems
of the first to third embodiments, the second lens unit (Gr2) as the
focusing lens unit than to use the first lens unit (Gr1), because this
helps reduce the load to be borne by the driving mechanism for the
focusing lens unit.
One type of aberration that occurs during image blur compensation is the
off-axial image-point movement error. This aberration indicates the degree
of over- or undercorrection of off-axial image-points that remains even
when axial image-points are corrected properly by the decentering of the
image blur compensating lens unit. This aberration depends principally on
the distortion occurring in the focusing lens unit (GF or Gf) disposed on
the object side of the image blur compensating lens unit (GB or Gb), and
on the distortion occurring in the image blur compensating lens unit (GB
or Gb). Accordingly, by limiting the distortion occurring in the image
blur compensating lens unit (GB or Gb) within an appropriate range, it is
possible to reduce the off-axial image-point movement error. Furthermore,
since the distortion occurring over the entire zoom lens system is
properly corrected, it is possible, by reducing the total distortion
occurring in the focusing lens unit (GF or Gf), in the image blur
compensating lens unit (GB or Gb), and in the last lens unit (GR), to
reduce the off-axial image-point movement error. From this point of view,
it is preferable that at least one of Conditions (4) and (5) below be
fulfilled.
-1.5<fB/fR<-0.3 (4)
0.8<fB/fW<4.0 (5)
where
fB represents the focal length of the image blur compensating lens unit (GB
or Gb);
fR represents the focal length of the last lens unit (GR); and
fW represents the focal length of the entire zoom lens system at the
wide-angle end [W].
Condition (4) defines the condition to be fulfilled to keep the ratio of
the optical power of the last lens unit (GR) to that of the image blur
compensating lens unit (GB or Gb) in an appropriate range. If the upper
limit of Condition (4) is exceeded, the optical power of the image blur
compensating lens unit (GB or Gb) is too weak as compared with that of the
last lens unit (GR), with the result that too little aberration is left to
be corrected by the image blur compensating lens unit (GB or Gb). Thus, it
is impossible to obtain an appropriate distortion coefficient in the image
blur compensating lens unit (GB or Gb) that is said to be required to
cancel out the off-axial image-point movement error occurring during image
blur compensation. In contrast, if the lower limit of Condition (4) is
exceeded, the optical power of the image blur compensating lens unit (GB
or Gb) is too strong as compared with that of the last lens unit (GR),
with the result that excessively large distortion occurs in the image blur
compensating lens unit (GB or Gb). As a result, the amount of distortion
that the last lens unit (GR) needs to correct to reduce the distortion
over the entire zoom lens system becomes too small, which makes it
impossible to correct the distortion over the entire zoom lens system
properly.
Condition (5) defines the condition to be fulfilled to keep the optical
power of the image blur compensating lens unit (GB or Gb) in an
appropriate range. If the upper limit of Condition (5) is exceeded, the
optical power of the image blur compensating lens unit (GB or Gb) is too
weak, with the result that image-blur-compensation sensitivity is too low.
This makes it necessary to increase the movement stroke through which the
image blur compensating lens unit (GB or Gb) is decentered and thus
increase the diameter of the image blur compensating lens unit (GB or Gb).
In contrast, If the lower limit of Condition (5) is exceeded, the optical
power of the image blur compensating lens unit (GB or Gb) is too strong,
with the result that that image-blur-compensation sensitivity is too high.
In this case, it is possible to reduce the movement stroke through which
the image blur compensating lens unit (GB or Gb) is decentered, and
therefore it is not necessary to increase the diameter of the image blur
compensating lens unit (GB or Gb). However, it is necessary to increase
the positioning accuracy with which the image blur compensating lens unit
(GB or Gb) is decentered, and this may require positioning accuracy that
exceeds the performance limit of the detection system used, or incur an
increase in the manufacturing cost.
Within the range defined by Condition (5), it is more preferable that
Condition (5') below be fulfilled. Fulfillment of Condition (5') makes it
possible to realize a zoom lens system that provides higher positioning
accuracy.
1.0<fB/fW<4.0 (5')
Note that, in the zoom lens systems of the first to third embodiments, the
zoom units are composed solely of refracting lens elements that deflect
incoming rays through refraction. However, the zoom units may include, for
example, diffracting lens elements that deflect incoming rays through
diffraction, refracting-diffracting hybrid-type lens elements that deflect
incoming rays through the combined effect of refraction and diffraction,
or the like.
Hereinafter, examples of zoom lens systems having an image blur
compensation function according to the present invention will be presented
with reference to their construction data, graphic representations of
aberrations, and other data. Tables 1 to 3 show the construction data of
the first to third embodiments, respectively. In the construction data of
each embodiment, ri (i=1, 2, 3, . . . ) represents the radius of curvature
of the ith surface counted from the object side, and di (i=1, 2, 3, . . .
) represents the ith axial distance counted from the object side (before
decentering). For each of the axial distances that vary with zooming (i.e.
variable axial distances), three values are listed that represent, from
left, the actual surface-to-surface distance between the relevant lens
units at the wide-angle end [W], the same distance at the middle focal
length (M), and the same distance at the telephoto end [T]. Ni (i=1, 2, 3,
. . . ) and vi (i=1, 2, 3, . . . ) represent the refractive index (Nd) and
the Abbe number (vd), respectively, for the d-line of the ith lens element
counted from the object side. Also listed together with the construction
data are the focal lengths f and the F numbers FNO of the entire zoom lens
system at the wide-angle end [W], at the middle focal length (M), and at
the telephoto end [T].
Furthermore, a surface whose radius of curvature ri is marked with an
asterisk (*) is an aspherical surface, whose surface shape is defined by
Formula (AS) below. The data of the aspherical surfaces are also listed
together with the construction data, and Table 4 lists the values
corresponding to Conditions noted above as observed in each embodiment.
##EQU1##
where X represents the displacement from the reference surface along the
optical axis:
Y represents the height in a direction perpendicular to the optical axis;
C represents the paraxial curvature;
.epsilon. represents the quadric surface parameter; and
Ai represents the aspherical coefficient of the ith order.
FIGS. 2A to 2I, 3A to 3I, 9A to 9I, 10A to 10I, 16A to 16I, and 17A to 17I
are graphic representations of the aberrations observed in the embodiments
before decentering (i.e. in the normal state). Of these, FIGS. 2A to 2I,
9A to 9I, and 16A to 16I are graphic representations of the longitudinal
aberrations observed before decentering (i.e. in the normal state) in the
infinite-distance shooting condition in the first to third embodiments.
FIGS. 3A to 3I, 10A to 10I, and 17A to 17I are graphic representations of
the longitudinal aberrations observed before decentering in the
closest-distance shooting condition (the object distance=1 m) in the first
to third embodiments.
FIGS. 2A to 2C, 3A to 3C, 9A to 9C, 10A to 10C, 16A to 16C, and 17A to 17C
graphic representations of the aberrations observed at the wide-angle end
[W] in the normal state. FIGS. 2D to 2F, 3D to 3F, 9D to 9F, 10D to 10F,
16D to 16F, and 17D to 17F are graphic representations of the aberrations
observed at the middle focal length (M) in the normal state. FIGS. 2G to
2I, 3G to 3I, 9G to 9I, 10G to 10I, 16G to 16I, and 17G to 17I are graphic
representations of the aberrations observed at the telephoto end [T] in
the normal state.
FIGS. 2A, 2D, 2G; FIGS. 3A, 3D, 3G; FIGS. 9A, 9D, 9G; FIGS. 10A, 10D, 10G;
FIGS. 16A, 16D, 16G; and FIGS. 17A, 17D, 17G show spherical aberration and
sine condition. In these diagrams, the solid line (d) represents the
spherical aberration for d-line and the broken line (SC) represents the
sine condition. FIGS. 2B, 2E, 2H; FIGS. 3B, 3E, 3H; FIGS. 9B, 9E, 9H;
FIGS. 10B, 10E, 10H; FIGS. 16B, 16E, 16H; and FIGS. 17B, 17E, 17H show
astigmatism (Y' represents the image height). In these diagrams, the
broken line (DM) and the solid line (DS) represent the astigmatism for
d-line on the meridional plane and on the sagittal plane, respectively.
FIGS. 2C, 2F, 2I; FIGS. 3C, 3F, 3I; FIGS. 9C, 9F, 9I; FIGS. 10C, 10F, 10I;
FIGS. 16C, 16F, 16I; and FIGS. 17C, 17F, 17I show distortion (Y'
represents the image height).
FIGS. 4A to 4E, 5A to 5E, 6A to 6E, 7A to 7E, 11A to 11E, 12A to 12E, 13A
to 13E, 14A to 14E, 18A to 18E, 19A to 19E, 20A to 20E, and 21A to 21E
show the aberrations observed before and after decentering (in the normal
state or during image blur compensation) in the embodiments. Of these,
FIGS. 4A to 4E, 5A to 5E, 11A to 11E, 12A to 12E, 18A to 18E, and 19A to
19E show the lateral aberrations observed on the meridional plane before
and after decentering in the infinite-distance shooting condition in the
embodiments. FIGS. 6A to 6E, 7A to 7E, 13A to 13E, 14A to 14E, 20A to 20E,
and 21A to 21E show the lateral aberrations observed on the meridional
plane before and after decentering in the closest-distance shooting
condition in the embodiments. FIGS. 4A to 4E, 5A to 5E, 6A to 6E, and 7A
to 7E show the aberrations observed in the first embodiment, FIGS. 11A to
11E, 12A to 12E, 13A to 13E, and 14A to 14E show the aberrations observed
in the second embodiment, and FIGS. 18A to 18E, 19A to 19E, 20A to 20E,
and 21A to 21E show the aberrations observed in the third embodiment.
FIGS. 4A to 4E, 6A to 6E, 11A to 11E, 13A to 13E, 18A to 18E, and 20A to
20E show the aberrations observed at the wide-angle end [W], and FIGS. 5A
to 5E, 7A to 7E, 12A to 12E, 14A to 14E, 19A to 19E, and 21A to 21E show
the aberrations observed at the telephoto end [T]. FIGS. 4A to 4C, 5A to
5C, 6A to 6C, 7A to 7C, 11A to 11C, 12A to 12C, 13A to 13C, 14A to 14C,
18A to 18C, 19A to 19C, 20A to 20C, and 21A to 21C show the lateral
aberrations observed at image heights Y'=+12, 0, -12 during image blur
compensation where an image blur of 0.7.degree. is being compensated {i.e.
during image blur compensation where the image blur compensating lens unit
is in a state for compensating an image blur of 0.7.degree. (=0.0122173
rad)}; and FIGS. 4D and 4E, 5D and 5E, 6D and 6E, 7D and 7E, 11D and 11E,
12D and 12E, 13D and 13E, 14D and 14E, 18D and 18E, 19D and 19E, 20D and
20E, and 21D and 21E show the lateral aberrations observed at image
heights Y'=+12, 0 in the normal state.
Table 5 lists the off-axial image-point movement errors and axial lateral
chromatic aberrations observed during image blur compensation where an
image blur of 0.7.degree. is being compensated in the embodiments. In
Table 5, the values grouped under [W], [M], and [T] represent the
off-axial image-point movement errors (mm) and axial lateral chromatic
aberrations (mm) observed at the wide-angle end, at the middle focal
length, and at the telephoto end, respectively. Moreover, in Table 5, for
each of the three focal length conditions mentioned above, three values
are given that are, from above, the value at an image height Y'=12 mm
(+12, 0) on the meridional plane, the value at an image height Y'=-12 mm
(-12, 0) on the meridional plane, and the value at an image height Y'=12
mm (0, +12) {note that negative and positive errors or aberrations appear
symmetrically} on the sagittal plane. In addition, axial lateral chromatic
aberrations are calculated as differences between aberrations for the d-
and g-lines.
FIG. 22 is a block diagram showing the control structure for moving the
image blur compensating lens unit in the zoom lens system of the first
embodiment. An image blur detecting sensor 101 is either incorporated in
the lens unit or provided separately therefrom so as to detect the
magnitude and direction of an image blur. The detection results are fed to
a CPU 100, which in response outputs to a driver 102 a control signal
indicating the distance and direction through and in which a driving
actuator 103 is to be driven. The driver 102, in accordance with the
control signal fed from the CPU 100, generates driving pulses for driving
the driving actuator 103. The driving actuator 103, in accordance with the
driving pulses, moves the image blur compensating lens unit through the
specified distance in the specified direction that is perpendicular to the
optical axis so as to achieve image blur compensation.
Note that a common stepping motor or a piezoelectric actuator using a PZT
(lead titanate zirconate) device may be used as the driving actuator 103.
Furthermore, when the zoom lens system of the first embodiment is applied,
for example, to an interchangeable lens for a single-lens reflex camera,
the CPU 100 and the image blur detecting sensor 101 may be provided either
in the lens or in the camera body.
TABLE 1
______________________________________
Construction Data of Embodiment 1
(positive-negative-positive-positive-negative)
f = 22.50 .about. 69.99 .about. 214.92
FNO = 4.60 .about. 6.20 .about. 7.69
______________________________________
Radius of Axial Refractive Abbe
Curvature Distance Index Number
______________________________________
r1 = 60.911
d1 = 0.960 N1 = 1.83350
.nu.1 = 21.00
r2 = 46.992
d2 = 7.455 N2 = 1.49310
.nu.2 = 83.58
r3 = -1095.638
d3 = 0.100
r4 = 37.500
d4 = 4.594 N3 = 1.49310
.nu.3 = 83.58
r5 = 74.197
d5 = 0.685 .about.
20.425 .about.
34.113
r6* = 37.598
d6 = 0.960 N4 = 1.77250
.nu.4 = 49.77
r7 = 12.530
d7 = 5.895
r8 = -31.071
d8 = 0.960 N5 = 1.77250
.nu.5 = 49.77
r9 = 123.107
d9 = 0.100
r10 = 24.579
d10 = 2.304 N6 = 1.83350
.nu.6 = 21.00
r11 = -116.103
d11 = 2.030
r12 = -18.519
d12 = 0.960 N7 = 1.75450
.nu.7 = 51.57
r13 = 219.304
d13 = 14.541 .about.
6.992 .about.
0.640
r14 = .infin.(Aperture
Stop S)
d14 = 0.100
r15 = 14.486
d15 = 3.420 N8 = 1.49310
.nu.8 = 83.58
r16 = -52.186
d16 = 0.100
r17 = 11.999
d17 = 2.255 N9 = 1.49310
.nu.9 = 83.58
r18 = 29.718
d18 = 1.636
r19* =
66.111
d19 = 1.912 N10 = 1.83400
.nu.10 = 37.05
r20* =
16.132
d20 = 5.200 .about.
2.775 .about.
2.300
r21 = 25.231
d21 = 2.955 N11 = 1.48749
.nu.11 = 70.44
r22 = -18.088
d22 = 2.000 N12 = 1.83350
.nu.12 = 21.00
r23 = -32.687
d23 = 3.678 .about.
2.065 .about.
1.000
r24* =
-64.281
d24 = 2.804 N13 = 1.84666
.nu.13 = 23.82
r25* =
-23.387
d25 = 3.437
r26 = -15.978
d26 = 0.960 N14 = 1.75450
.nu.14 = 51.57
r27 = -124.076
______________________________________
[Aspherical Coefficient of Surface r6]
.epsilon. =
1.0000
A4 = 0.83645300 .times. 10.sup.-5
A6 = 0.67353100 .times. 10.sup.-7
A8 = -0.10566100 .times. 10.sup.-8
A10 = 0.51276200 .times. 10.sup.-11
A12 = 0.88135000 .times. 10.sup.-15
[Aspherical Coefficient of Surface r19]
.epsilon. =
1.0000
A4 = -0.39985900 .times. 10.sup.-4
A6 = 0.21782000 .times. 10.sup.-6
A8 = 0.95114000 .times. 10.sup.-9
A10 = -0.20385600 .times. 10.sup.-10
A12 = -0.29974600 .times. 10.sup.-12
[Aspherical Coefficient of Surface r20]
.epsilon. =
1.0000
A4 = 0.77224600 .times. 10.sup.-4
A6 = 0.72183200 .times. 10.sup.-6
A8 = 0.51068600 .times. 10.sup.-8
A10 = 0.42389400 .times. 10.sup.-10
A12 = -0.73088800 .times. 10.sup.-12
[Aspherical Coefficient of Surface r24]
.epsilon. =
1.0000
A4 = -0.45652900 .times. 10.sup.-4
A6 = -0.51530100 .times. 10.sup.-6
A8 = -0.52845600 .times. 10.sup.-8
A10 = 0.41459300 .times. 10.sup.-10
A12 = -0.71354200 .times. 10.sup.-12
[Aspherical Coefficient of Surface r25]
.epsilon. =
1.0000
A4 = -0.34438900 .times. 10.sup.-4
A6 = -0.52934900 .times. 10.sup.-6
A8 = 0.50113400 .times. 10.sup.-9
A10 = -0.43265700 .times. 10.sup.-10
A12 = -0.20027900 .times. 10.sup.-14
______________________________________
TABLE 2
______________________________________
Construction Data of Embodiment 2 (positive-negative-positive-negative)
f = 22.51 .about. 70.01 .about. 215.46
FNO = 4.60 .about. 6.20 .about. 7.20
______________________________________
Radius of Axial Refractive Abbe
Curvature Distance Index Number
______________________________________
r1 = 88.793
d1 = 2.611 N1 = 1.83350
.nu.1 = 21.00
r2 = 69.117
d2 = 7.307 N2 = 1.49310
.nu.2 = 83.58
r3 = 2587.322
d3 = 0.100
r4 = 57.723
d4 = 4.935 N3 = 1.49310
.nu.3 = 83.58
r5 = 127.503
d5 = 0.836 .about.
34.003 .about.
58.967
r6* = 44.870
d6 = 0.850 N4 = 1.77250
.nu.4 = 49.77
r7 = 13.694
d7 = 6.909
r8 = -34.456
d8 = 0.850 N5 = 1.77250
.nu.5 = 49.77
r9 = 423.481
d9 = 0.100
r10 = 28.647
d10 = 2.822 N6 = 1.83350
.nu.6 = 21.00
r11 = -177.318
d11 = 1.954
r12 = -22.331
d12 = 0.850 N7 = 1.75450
.nu.7 = 51.57
r13 = 370.501
d13 = 14.970 .about.
6.662 .about.
0.612
r14 = .infin.(Aperture
Stop S)
d14 = 0.100
r15 = 14.072
d15 = 3.047 N8 = 1.49310
.nu.8 = 83.58
r16 = -82.820
d16 = 0.617
r17 = 12.765
d17 = 3.750 N9 = 1.49310
.nu.9 = 83.58
r18 = 41.408
d18 = 1.122
r19* =
127.264
d19 = 1.319 N10 = 1.83400
.nu.10 = 37.05
r20* =
18.577
d20 = 7.896 .about.
3.230 .about.
2.219
r21 = 24.782
d21 = 3.196 N11 = 1.48749
.nu.11 = 70.44
r22 = -20.010
d22 = 1.500 N12 = 1.83350
.nu.12 = 21.00
r23 = -35.612
d23 = 4.022
r24* =
-52.169
d24 = 3.637 N13 = 1.84666
.nu.13 = 23.82
r25* =
-20.109
d25 = 1.277
r26 = -15.605
d26 = 0.850 N14 = 1.75450
.nu.14 = 51.57
r27 = -183.819
______________________________________
[Aspherical Coefficient of Surface r6]
.epsilon. =
1.0000
A4 = 0.84449900 .times. 10.sup.-5
A6 = 0.63551500 .times. 10.sup.-8
A8 = 0.20154300 .times. 10.sup.-11
A10 = -0.14396400 .times. 10.sup.-12
A12 = 0.17773000 .times. 10.sup.-14
[Aspherical Coefficient of Surface r19]
.epsilon. =
1.0000
A4 = -0.40326000 .times. 10.sup.-4
A6 = 0.26710500 .times. 10.sup.-6
A8 = 0.12593500 .times. 10.sup.-8
A10 = -0.19817800 .times. 10.sup.-10
A12 = -0.47458300 .times. 10.sup.-12
[Aspherical Coefficient of Surface r20]
.epsilon. =
1.0000
A4 = 0.82195200 .times. 10.sup.-4
A6 = 0.74794100 .times. 10.sup.-6
A8 = 0.70469000 .times. 10.sup.-8
A10 = 0.24450700 .times. 10.sup.-10
A12 = -0.47794400 .times. 10.sup.-12
[Aspherical Coefficient of Surface r24]
.epsilon. =
1.0000
A4 = -0.51552400 .times. 10.sup.-4
A6 = -0.42163600 .times. 10.sup.-6
A8 = -0.18955400 .times. 10.sup.-8
A10 = 0.71695600 .times. 10.sup.-10
A12 = -0.17765700 .times. 10.sup.-11
[Aspherical Coefficient of Surface r25]
.epsilon. =
1.0000
A4 = -0.32518400 .times. 10.sup.-4
A6 = -0.37081400 .times. 10.sup.-6
A8 = 0.25625300 .times. 10.sup.-8
A10 = -0.42716300 .times. 10.sup.-10
A12 = -0.31376100 .times. 10.sup.-12
______________________________________
TABLE 3
______________________________________
Construction Data of Embodiment 3
(positive-negative-positive-positive-negative)
f = 22.50 .about. 70.07 .about. 214.94
FNO = 4.60 .about. 6.20 .about. 7.20
______________________________________
Radius of Axial Refractive Abbe
Curvature Distance Index Number
______________________________________
r1 = 62.115
d1 = 0.850 N1 = 1.83350
.nu.1 = 21.00
r2 = 49.652
d2 = 6.692 N2 = 1.49310
.nu.2 = 83.58
r3 = 1351.225
d3 = 0.100
r4 = 44.800
d4 = 4.254 N3 = 1.49310
.nu.3 = 83.58
r5 = 96.785
d5 = 0.858 .about.
22.154 .about.
40.664
r6* = 35.557
d6 = 0.850 N4 = 1.77250
.nu.4 = 49.77
r7 = 12.555
d7 = 5.826
r8 = -38.037
d8 = 0.850 N5 = 1.77250
.nu.5 = 49.77
r9 = 53.529
d9 = 0.100
r10 = 24.577
d10 = 2.601 N6 = 1.83350
.nu.6 = 21.00
r11 = -208.564
d11 = 2.468
r12 = -18.453
d12 = 0.850 N7 = 1.75450
.nu.7 = 51.57
r13 = -1321.161
d13 = 0.100 .about.
0.100 .about.
0.100
r14 = 39.994
d14 = 1.004 N8 = 1.77250
.nu.8 = 49.77
r15 = 51.421
d15 = 14.126 .about.
6.354 .about.
0.631
r16 = .infin.(Aperture
Stop S)
d16 = 0.100
r17 = 14.027
d17 = 3.681 N9 = 1.49310
.nu.9 = 83.58
r18 = -550.070
d18 = 0.100
r19 = 12.779
d19 = 4.500 N10 = 1.49310
.nu.10 = 83.58
r20 = -56.499
d20 = 0.867
r21* =
-32.009
d21 = 2.058 N11 = 1.83400
.nu.11 = 37.05
r22* =
49.010
d22 = 4.775 .about.
0.100 .about.
0.580
r23 = 27.407
d23 = 2.594 N12 = 1.48749
.nu.12 = 70.44
r24 = -43.211
d24 = 2.579 N13 = 1.83350
.nu.13 = 21.00
r25 = -89.260
d25 = 4.047 .about.
4.835 .about.
3.318
r26* =
-27.032
d26 = 2.611 N14 = 1.84666
.nu.14 = 23.82
r27* =
-16.154
d27 = 1.161
r28 = -11.853
d28 = 0.850 N15 = 1.75450
.nu.15 = 51.57
r29 = -38.069
______________________________________
[Aspherical Coefficient of Surface r6]
.epsilon. =
1.0000
A4 = 0.66392800 .times. 10.sup.-5
A6 = -0.35561500 .times. 10.sup.-7
A8 = 0.28951400 .times. 10.sup.-9
A10 = -0.11033500 .times. 10.sup.-11
A12 = 0.54879700 .times. 10.sup.-14
[Aspherical Coefficient of Surface r21]
.epsilon. =
1.0000
A4 = 0.59076200 .times. 10.sup.-4
A6 = 0.82572900 .times. 10.sup.-6
A8 = -0.12752000 .times. 10.sup.-7
A10 = -0.87916000 .times. 10.sup.-10
A12 = 0.15020400 .times. 10.sup.-11
[Aspherical Coefficient of Surface r22]
.epsilon. =
1.0000
A4 = 0.19223400 .times. 10.sup.-3
A6 = 0.43866100 .times. 10.sup.-6
A8 = 0.59818500 .times. 10.sup.-7
A10 = -0.16565500 .times. 10.sup.-8
A12 = 0.15712800 .times. 10.sup.-10
[Aspherical Coefficient of Surface r26]
.epsilon. =
1.0000
A4 = -0.10553800 .times. 10.sup.-3
A6 = -0.10910900 .times. 10.sup.-5
A8 = 0.43503400 .times. 10.sup.-7
A10 = -0.82295000 .times. 10.sup.-9
A12 = 0.40413400 .times. 10.sup.-11
[Aspherical Coefficient of Surface r27]
.epsilon. =
1.0000
A4 = -0.69947800 .times. 10.sup.-4
A6 = -0.87885400 .times. 10.sup.-6
A8 = 0.29904700 .times. 10.sup.-7
A10 = -0.50361200 .times. 10.sup.-9
A12 = 0.20882900 .times. 10.sup.-11
______________________________________
TABLE 4
______________________________________
<<Values Corresponding to Conditions (1) to (5')>>
Cond. Emb. 1 Emb. 2 Emb. 3
______________________________________
(1) f1/fW 73.72/22.50 =
110.96/22.5 =
82.00/22.5 =
3.28 4.93 3.64
(2) f2/fW -11.50/22.50 =
-13.28/22.5 =
-11.86/22.5 =
-0.51 -0.59 -0.53
(3) LBW/Y 18.00/17.25 =
18.29/17.25 =
18.00/17.25 =
(3')
max 1.04 1.06 1.04
(4) fB/fR 39.34/-67.67 =
39.26/-59.32 =
52.79/-48.13 =
-0.58 -0.66 -1.09
(5) fB/fW 39.34/22.5 =
39.26/22.5 =
52.79/22.5 =
(5') 2.33 1.74 2.35
______________________________________
TABLE 5
______________________________________
Off-axial Image-point Movement Error and
Axial Lateral Chromatic Aberration (.theta. = 0.7.sup..degree.)
Off-axial Image-point Axial Lateral Chromatic
Movement Error (mm) Aberration (mm)
______________________________________
Emb.1 [W] (+12, 0) 0.0118 0.013
(-12, 0) 0.0146
( 0,+2) 0.0335
[M] (+12, 0) 0.0101 0.015
(-12, 0) 0.0207
( 0,+2) 0.0226
[T] (+12, 0) 0.0007 0.023
(-12, 0) 0.0449
( 0,+2) 0.0218
Emb.2 [W] (+12, 0) 0.0041 -0.003
(-12, 0) -0.0014
( 0,+2) 0.0303
[M] (+12, 0 0.0030 0.008
(-12, 0) 0.0135
( 0,+2) 0.0200
[T] (+12, 0) -0.0072
0.022
(-12, 0) 0.0505
( 0,+2) 0.0221
Emb.3 [W] (+12, 0) 0.0020 0.003
(-12, 0) 0.0041
( 0,+2) 0.308
[M] (+12, 0) 0.0060 0.007
(-12, 0) 0.0246
( 0,+2) 0.0231
[T] (+12, 0) -0.0137
0.015
(-12, 0) 0.0444
( 0,+2) 0.0182
______________________________________
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